I would stick to savagery till you hit 40. For lvl 31 i would go for a build like this:
https://builder.returnofreckoning.com/c ... ,5205,5196
At lvl 35 i would switch to this:
https://builder.returnofreckoning.com/c ... ,5188,5196 and then continue with savagery too get TB again.
I tried sav, brut and also stance swapping in mid tier, my conclusion is stick with sav for st, just take Growing Instability tactic form brut, stance swapping is only good after 40. TB, Cutting Claw, hd and spamming Rend will deal nice dmg. Swapping to monstro only for some selfheal if needed and using Ferocious Assult. Mara might not see the biggest numbers but you will be very effictive in killing stuff.
I played most of the time as duo, 3man or 6man in midtier and was able to top charts with kills, dmg and effective dmg in sc as savagery mara many times. Having guard and heal will allow you to go full mad mode. But it will work decent even played solo. Without healers Warped Flesh worked rly good for me. Maras dmg come from crits, so critchance is your best choice for increasing dmg.
For roaming in rvr you will have a hard time against wh, if you manage to disarm them before they kill you you do have a chance in a 1v1. Cutting Claw is undefendable, and Rend wont allow them to get into stealth. Wl with pet dmg build and kd will dominate you, otherwise its a fair fight. Healers who underestimate you can be killed with TB and hd. With charge and your m1 you can hunt down ranged classes pretty good. As you wrote already, mara is not the best solo roamer (but not the worst either). It works rly good as duo with a tank. Savagery and stacking parry + toughness might be the best option for soloing.
For fast t4 gearing i can recommend taking 2x sent, cloak and ring with +54 mp of lotd and 5x bloodlord and saving all crest for 5x sov.
I hope this helps and i am rly looking forward to see a mara video coming.