I find that most of my favourite variants don't need any changes (what can be done with Mauler D? It is already perfect!). So, i will post changes for the things I like but find some of equipment not matching.
Vulture B: SSRMs to SRMs. Now you need some skill for it.
Vulture Prime: LRM15+DHSs
Oro E: -BAP, +GECM or better lasers (if possible) or +Armour.
Huit B (Anaconda?): HS to DHS.
Thanatos A: back to HGauss.
Thanatos C: no flamers, + DHS. Not sure...
NCat aka "Thermal lance": -2CLPL, +2CHLL, +4 DHS. I will lolalpha your Atlas =D.
Awesome D: no LAMS (useless there), more DHS.
P.S. Usually, I find most variants to be good as they are.