I'd recommend trying BIAB first, since it's by far the cheapest and easiest route to get into all-grain brewing. It won't require all of the extra equipment, just a mesh bag and maybe an extra pot to heat sparge water.
A few tips regarding BIAB:
Make sure to double-crush your grains and use a large enough bag for your pot. When draining, squeeze what you can out of the grains to get the best efficiency. Some people don't sparge when doing BIAB brewing, but I've done dunk-sparging (just heat sparge water, as you would with traditional AG brewing, and after draining the bag, dunk it into the sparge water for 10-15 minutes, then squeeze the bag and add the runnings to your kettle). Last time was only my second BIAB attempt, and (according to my calculations) I hit 89% extraction efficiency. That's pretty unusual, I'm sure, but it's possible. Have an extra, clean bucket handy for holding your sparge water and dunking, or just to keep the bag from dripping all over the place. And just use a small pot lid to press/squeeze the bag.
Going full-blown AG, you'll be pouring quite a bit of cash at the equipment. Larger kettle, HLT, MLT, tubing, pumps, coolers, burners, etc. Try BIAB first to see if you think you'll like it, then worry about shelling out for traditional AG. You may find you just want to stick with BIAB, or use it to do partial/mini-mash brews.