Depends on what your trying to build. Absolute most power or good reliable power. Turbo will net the most power but there have been a lot more guys blow up there V6 with turbos then with superchargers. I have 134,000 miles on my 4.0 with 104,000 miles my X-Charger currently running 330RWHP and I pound the crap out of it! I don't know of any Turbo 4.0 lasting anywhere near that long but they sure put out some high horse power for a while.
haha that made me laugh. And how much does OP want to spendThat's because you're bi-winning.