it comes down to personal preferance, but i agree with OPT & have been using bongos since It came out.( I miss Flexbar)

For the rest of the UI, I pick mods I like & configure them the way I like. I don't like the packs of mods, I try to keep it minimal.

Some things I can't live without:
1. Bongos (Bar Mod)
2. Pitbull (Unit Frames)
3. Proximo(Arena PVP Target List)
4. TwoBoxToolkit (Mostly use this for the whisper/quest accept functionality)
5. Bagnon. (Inventory /bag deal)


Some things I am still looking for:
A good Small lightweight Tooltip addon that lets the tooltip follow mouse. Small/simple/low memory footprint is important.
(Currently Using an old version of tinytip that throws errors, but it did exactly what i wanted till it broke)

My clones have all of the above, but that's it for mods, I REALLY try to keep thier UI Simple & uncluttered even more than my main.