That $150 used bike I bet will still outlast a $150 brand new bike from walmart.
those walmart mountain bikes are junk if you take them off the pavement. not worth upgrading a single part on them...
beefy hard tails are pretty popular now days, snubbyfan. they call them "all mountain".
im now riding a steel hardtail with a slackish head angle, 140mm fork with 2.3" tires. brought the fun back to the same old trails.