Built in vacuum is 100% better than any other type of vacuum, not even close.
The reason some have crappy suction is people undersize their unit. Buy a big unit with 2 or 3x the suction of a portable vac and your are set.
Remember that everything that goes in the hose on a built in stays in the cannister or if it makes it through the filter it vents outside of your house.
2017 VW Jetta 1.4T (winter car)
2010 F-350 Nortruck Tool Shed
2007 BMW 5 (Wifey's)
2004 Audi A4 1.8T 6spd Stage III w/ Meth
1985 F-250 6.9L IDI w/ATS turbo