Windigo = good stats , easier to upgrade , easy to aqcuire , tho resis lacks at high ranks unless u have good res mods , (good for heat / phys build )
Naga = good stats , lighter than windigo , easy to aquire , easy to upgrade , resis lacks at high ranks (good for phys / ene build)
mpv = late game , stats lacks abit than windigo , make sure u have decent mods , harder to acquire but its good for (phys / heat builds)
Go for windigo for now , youll die with mpv and low stats trust me , i have an lpv at my 2nd mech but i dont use it for now since i dont have good mod set
(edit)
Some torsos that can be also used in phys mech
Nightmare = Cheap / easy to aqcuire , good heat stats , same as windigo for resistance , lightweight , but would lack resis at high rank
Monkey torsos Ene/Heat = High hp , (downside : abit heavy) ,lacks resis , decent stats tho