There are 3 main types of buckle.
The cheapest 4 point has a normal seatbelt type buckle with the shoulder and lap belts on each side sewn together. You have to put the harness on like a waitstcoat, threading your arms through then buckling it under your guts. Not bad for a track day but far from ideal in competition. They are limited to 4 points, ie; no crutch strap available.

The next type is the 'Nascar' or 'speedway' buckle. They are 4 or 5 point. The buckle is an ugly external latch mechanism that looks like a rat trap. You have to 'load' all the belt buckles onto the latch one at a time then clip the clasp over. They are ideal in dirty situations as mud can be washed out of the latch easily. They can be inadvertently unlatched by your sleeve in a panic steering manouver however and look like shit.

Widely recognised as the best option is a rotary buckle or 'aircraft' style. They can be 4, 5 or 6 point. You can start as a 4 point then upgrade to a 5 or 6 when you get race seats by just purchasing the crutch strap if you get the right type of buckle. These are the easiest to put on and the easiest/quickest to undo in an emergency.