Alpha only gives the first stage of Rotting, which…does nothing. Get yourself some Regen and that’ll cancel it out.
(Medical gives Unstable Genetics too, and most of the mental disads.)
If I planned on a character mutating xemself from the start, I’d go with Robust Genetics, Night Vision, and probably Fast Healer. Disease Resist and Poison Resist are good ones to have around too.
In terms of what mutation category to shoot for, that depends on your preferences. Melee fighters work well with Beast, and I built two of the four top-tiers with melee in mind. Cephalopod can be pretty nice if you start with extra ST, since the tentacle-attacks use half your ST as the damage.