I use the http://www.nexusmods.com/skyrim/mods/19337/? to compare different packs and decide which goes where. (Careful when looking at plants or other items that use alpha channels, since alpha is off by default, making some good textures look worse than vanilla unless you toggle alpha.) You must also allow for color and contrast differences across your monitor/lcd, which could make a mod on one side look falsely better than another (just switch order of viewing if in doubt and see if the better one looks good no matter where it is on the screen).
Generally speaking, though, the installer tab in Wrye Bash is where I establish texture and mesh hierarchy, and the mods tab is for load order and bash patching. The two are completely different, so you can usually place replacer packs strategically to get what you want, regardless of esp load order. Before delving into detailed textures or comparisons, I place large packs high (low number) in the installer tab, just after vanilla oblivion bsa replacers and main patches, and then progress to ever more specialized replacers. These all come before "play" mods and nature/weather overhauls, allowing the latter to overwrite the earlier textures and "insist" on their own styles. If I like a texture pack more than a mod's own graphics, I'll replace the ones in the mod directly in a new BAIN so they do not overwrite my favs. So, say, a nature-oriented overhaul may use plant graphics from my preferred replacer mod in that area, or B&M the fire textures from my favorite replacer of those.
No reason one cannot also mix the order any old way in the installer tab, ordering some mods before replacers, and others after. But that for me is confusing at times, so I keep a strict hierarchy for sake of ease. Hard part, really, is figuring out your preferences, and so far the linked tool is the best way I've found to do it in an orderly fashion. Pain in the hind quarters to actually do, however, so I only spend time comparing major stuff and generally trust my specialized replacers to be better than generic packs.