Wow. Hadn't noticed this thread :\
All the twisty puzzles I own are:
* a stickerless Dayan Zhanchi 3x3
* an AkunDa 3D Puzzle (a core-less 3x3 with lid that opens when you solve it)
* a Christmas-themed keychain picture cube
* a worn Rubik's brand 4x4
* a stickerless Diansheng 5x5 with the orange-blue-yellow corner broken
* a Shengshou 6x6 with some internal parts missing (works fine, though...just gotta be careful)
* a Shengshou 7x7
* an MF8 Square-1
I also borrowed my girlfriend's Megaminx (unknown brand) for the past few days, and I learned my way around it fairly quickly.
My methods are:
* 3x3 speed - CFOP with F2L Partial Edge Control, COLL, and 2-look PLL (sometimes I do Partial Edge Control, other times not)
* 3x3 FMC/other - Heise method (not good at FMC, though)
* 4x4 and up - Yau method (variant of reduction where the first 3 cross edge pairs are solved before the centers, and the 4th is solved before edge pairing) for 4x4 and up
* Megaminx - LBL (I guess) with corner commutators and 3-edge cycles for LL (I sometimes work in a sort of hybrid F2L+blockbuilding aspect for solving until LL)
* Square-1 - Corner-edge pairing (see 6th method on
this page)
My average 3x3 time is around the 30s range. It varies.