If you start from scratch on Addons I'd say start fresh, take some that take a lot of configuration but pay off well.

Unit Frames: Pitbull
turn it any way you like, but there is no other unitframes mod that is more customizable than thisone. U can do anything with it, really

Bar addons: Trinity Bars
until recently i was using bongos myself, and when i swapped to trinity bars i was like 'wtf, this is complicated', but after an hour or 2 of messing around on 1 char, I had all the settings done. The most 'cool' thing I found out was that internally it seems to all work with macros, because when I copy pasted my WTF contents to my other accounts/names of chars, they had EXACTLY the same spells and macros in the same place, so I didnt have to edit anything.

Btw! what I said about macros, u can 'macro' every spell internally on the addon as well, so u have unlimited buttons and unlimited macros with trinity bars. I used both general and personal macros, both were full, when i was using bongos and I still lacked stuff. Now with trinity I use 0 (ZERO) macros, because theyre all in the bars. It's quite amazing really.

Other than those 'main' addons theres a load i use for personal stuff, but some of them:
fubar, omen, sw_stats, recap, atlasloot, questhelper, auctioneer, dotimer, cartographer, ct_mailmod, naturenemycastbar
CCBreaker, deadly bossmods, itemrack, gatherer, healbot, informant, monkeyquest, quartz, ratingbuster, smartbuff, proximu preformAVenabler, Prat, simpleminimap, totemtimers

Hope that helps