I seemed to crack an alloy frame every year until I switched to cro-mo(still runnin'solid 2-1/2yrs:thanks.243), so I would suggest steel, but there are a LOT of sick frames in both flavors out there well worthy of abuse!
This beauty on ebay which is prime example of fine quality T45 steel https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F114169750352