Something like a Poldiak GG ,EA , Roller, Morph, the list goes on and on lots of side button mods are available.
Also the "Fallen Angel" -- Electric Angel clone by EHPro. Most reviews say the quality is actually better than the Electric Angel. I find the side-bottom button a bit awkward, but this is an excellent, very high quality mech, that won't break the bank -- got mine for $39.95 from litecigusa.net, but I've recently seen it for less.
The Galileo by smoktech is a bottom magnet button, but the magnet is VERY strong, never fires accidentally while standing on its end -- also not expensive; I got mine from MadVapes for $34.95. It's very unique looking, and very comfy in the hand. It's the only mech I've ever seen that also has ego threading -- mostly irrelevant, I know, but it's a nice little extra in case you ever want to use something with ego threads, without needing an adapter.
Andria