I just got around to buying morrowind and the expansions, what mods would be the best if its my first time playing?

First time players usually like to play the game for awhile, so they can experience the original game and decide what they want to add.
My advice is to start small, or you'll get overwhelmed.
http://www.gamesas.com/index.php?/topic/1060141-mod-recommendations-for-new-players/page__p__15392814#entry15392814 has advice on what patches and tools you'll need to get started.
Along with lots of links to other players "Lists of Favourite Mods" and info on where to find graphical updates so the game doesn't look so old.

Better Bodies.
A head replacer of your choice.
The Code patch. (To fix a huge number of frustrating bugs).

The Vanilla graphics were poor when the game was released and you don't deserve to ever have see them now.

The bodies maybe, but the rest was considered cutting edge at the time from what I remember.

If there's one mod I'd start off with as a new player it would be a house mod in Seyda Neen, which can act as a base for your early explorations. It doesn't affect the vanilla game much but it's a nice addition and gives you a feeling of security and somewhere decent to stash your early loot. My own preference in that regard is Anastasio The Great's Hideout, which is underground and so changes very little, but there are a lot of others. It's a little cheat though (very little) because it gives you a silver sword and a few potions.

OTOH, you may prefer roughing it and having nowhere to lay your hat, except what you can find for yourself

It is safe and legal to assume ownership of a home, if the previous owner(s) have died. In other words, you don't have to use a house-mod to get a home in Seyda Neen.

Actually, no it is not safe and legal.
Almost every container in a home has Ownership on it. That makes all the items you place in those containers stolen items.

What happens with Ownership if the owner dies, or is dead when the game starts, like the tax-collector? I can't remember if he had a house in Seyda Neen or not.

Of course you don't need a house mod. But there's a big difference between some dusty old shack and a well-appointed, spacious house, with a few mannikins, some storage, maybe a pool to relax by. Depends whether you want authentic Morrowind or a bit of luxury.

The death of an NPC does not remove Ownership from anything.

can anyone give me the specific names of some good model changes?

http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=7459
http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=7984
http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=8737


Also, Vurt has many different types of new tree/mushroom replacers that are excellent: http://planetelderscrolls.gamespy.com/View.php?view=User.EntriesListing&id=444351

There are not too many mesh replacers (although more than I listed.) Mostly people focus on textures.

I'm very sorry, I didn't know that could happen. Thank you for correcting me.

Are the containers in the "inheritable" Seyda Neen & Balmora houses owned by anyone?

I don't know which houses you mean, but both Foryn Gilnith's shack and Hlaalo Manor have ownership on everything.
Basically any house, empty or not, has ownership on most things.

A few exceptions are the following safe houses: St. Delyn Waist North-Two apartment, the Abandoned Shack southwest from Gnaar Mok, and the Vacant Tower in Dagon Fel (although it has rats instead of storage)
The Strongholds that you can build if you join a Great House faction also are safe.

http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=3583
http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=3143
http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=8502
http://www.tesnexus.com/downloads/file.php?id=27167
http://translate.google.de/translate?hl=de&sl=ru&tl=en&u=http%3A%2F%2Fwww.fullrest.ru%2Fplugins%2Fbetters%2Fmorrowind%2FBetter_Item_pack_two.html (under "Files" right to "Info")

The original question is extremely vague. The mods you add depend entirely on what you want fom the game. Unfortunately, until you play it for a few dozen hours at the very least, you won't know what you really want or need to change. I'd avoid any kind of game-changing mods for a first play-through, and just experience the "vanilla" game for a while. The exceptions are: the Morrowind Patch Project (which replaces the Unofficial Patch) and the Morrowind Code Patch (a recent "miracle" mod which fixes a few issues that were beyond the reach of the Construction Set and traditional mods - it's modular, so you can decide what changes/fixes to make or not make).

I'd also suggest getting a "base" graphics replacer (I use Visual Packs) and a body replacer (Better Bodies has long been the standard, and there are newer higher resolution textures available for it). You can add all sorts of specific replacers afterwards (weapons, armor, clutter items - such as Ghostnull's Reflective Silverware, architecture, landscape, creatures, etc.), for anything that you feel needs "improving", and just overwrite the VP textures as needed. MGE allows you to extend the view distance out to "infinite" (I prefer a maximum fog distance of around 6 cells - a slightly hazy day), rather than the ever-present and claustrophbic fog which was necessary to maintain decent frame rates on the computers of that day. MGE can also render things like animated grass, which gives the MW landscape that same soft and undulating "cover" which did wonders to obscure the ugly and blocky ground in OB.

Once you're more familiar with the game, a good "levelling" mod (GCD, MADD, or other) will remove the chore of tracking "multipliers" and allow you to just forget about all that nonsense and play. Depending on your focus and interests, anything from combat enhancements, magic overhauls, additional NPCs, new quests, crafting and smithing options, companions (with or without quests), and major map expansions are all available (the first couple of map sections of the Morrowind mainland, the Tamriel Rebuilt project, are amazing), but you can spend so much time on all that mod content that you never really get to see the game as it was designed or intended.

Most of the bandit caves are safe for storage.

The shack left vacant by the tax collector incident has ownership on at least some of the containers. I made myself a "trivial" little mod that removes "ownership" from those particular containers, and just have to trust myself not to loot the meager posessions in them right in front of the resident before completing that mini-quest. I suppose it would be easy enough to replace the containers with unowned versions upon completing the quest, but I haven't felt the need to do so for my own use.

- Edited for cut & paste error; I duplicated the MCP instead of MPP and MCP.

Thanks Pluto & Kovacius.