Either way works for me. Personally I don't find the main all that engaging, but, whatever floats your boat. It's your game to play the way you want to.
1st play thru, reached lvl 48 when main quest line was finished. on 2nd play thru, reached lvl 62 before ending main quest. i think if you hold off on the main quest, you get a larger % of side quests and misc. quests.
There is a certain impatience to see the main quest play out the first time.
I'm certainly taking it much more leisurely now...
I'm at level 51, and I only just went to the Glowing Sea. Haven't done a lot with the Railroad, and only did the BoS far enough to get the armor. I've explored the whole map, but still have dozens of marked locations I haven't gone inside.
My first playthrough I was level 74 - 77 or so when I ran through three of the endings (some paths gave more exp than others, although I could have just done more side stuff along the way)....
My current playthrough I am level 102 and have not ticked off any faction yet ---- stringing them ALL along.
There are some questlines that make more sense if you have not already defeated the Institute, for example. Being told, like a simpleton, what a "synth" is, after you have been dealing with them for in-game months feels a bit odd.
I can say I wish I did more with the railroad and the institute before completing the main quest, since after the main quest I've struggling on finding other things to do, beside building a huge settlement on the island. I had done over 30 quest each for the brotherhood and the minutemen but only like 4 quest for the each the railroad and the institute and I'm only at level 53 so I felt like I robbed myself on getting to a higher level quicker by not doing more of the other twos quest. now its roaming aimlessly not knowing what to do.
Exactly this.
My advice would be to do the main quest until you unlock the Institute, then help the factions at your leisure. Don't rush to complete it because you'll have to pick sides, then be locked out of things that you could have done while you were still neutral.
I am lvl 180 with no decided ultimate faction.
I still get to enjoy all shops and side quests offered by all factions except Railroad. I am locked out of Raiload side quests due to P.A.M doing something spoilable. lol.
Like others said,
If you are not ready to finish your game it is best to keep as many options open as possible.
Nah. If you want better armor and weapons that you can get through the factions (i.e. Ballistic Weave, X60, etc...) or companions, sure, you can run through the questlines first, but its really not necessary. I didn't hit the main quests until well in to my 50's and I really didn't notice the difference. In fact, by the time I got to the Prydwen, I already had X-01 with hot-pink paint, so the X-60 was relatively moot.
I take breaks in between MQ's. So I spend more time doing SQ, misc or just explore. Last night, I explored parts of the Glowing Sea for the first time. Though when I made it to the half buried bell tower church and look down. I must of woken over a dozen angry ghouls running from left to right. I didn't have enough firepower to take them out, so I quickly got the heck out of there. Reminded me of the Will Smith movie Legend.
Once you get to a certain point in the main quest, there certainly is a reason to hold off as continuing will close off other options (basically you have to choose a side). I reached this point about 10 levels ago and have been roaming the countryside ever since. Once I get robot hacking, I'll probably continue on.
Also at the point I'm at I can use the perks from every single faction, and no faction is targeting me. I assume roaming is a little more difficult if the brotherhood (or whomever) is randomly targeting you (although blowing Vertibirds out of the sky is probably a lot of fun).
I also know that once I finish the main game, I probably won't play anymore, so that's a personal reason I hold off. If you are holding off on the main quest though, I do recommend at least playing far enough to reach the Institute, if only to get the synth relay grenades. They open up a fun and effective new battle mechanic. The institute also has crazy good armor at their shop.