Good option

If you do the math, both styles will have about the same contact area. The split end plugs will fit tighter, but I have seen them loosen faster due to pulling them in and out. With the contact, the entire shaft is not contacting the sides, just the tip where it is spread apart, unless it is a brand new battery. Overall, you just have to make sure the plugs are tight. Both styles will loosen over time.

I literally have 100’s like the Proteks if you need to buy in bulk. Never really had any loosening problems, but I don’t cycle them that often.

So now in 2021, is the consensus pro-bullet or anti-bullet for the common connection between the ESC and battery? So, let's say, if the hard LiPo pack has bullet tubes, then should the in/out normal connections--like if you were changing batteries, charging, etc--be the bullet/tubes over and over again, or should they be kind of a one-time-thing and put an upstream Deans or XT60 connector instead to handle the heavy swapping? Based on pictures, it seems that bullets-only is the "pro choice(?)," but I've also seen chassis pictures of pros' vehicles with Deans as well. So it's really a mixed bag. Basically, I am only set up to do bullets, but looking for longevity improvements; I don't want to wear down the battery tubes and end up with a loose connection that cannot be fixed. But maybe what Alexv2024 said in Post #15 is a good way of looking at it: by the time the tubes are worn out, the batteries are worn out as well and should be replaced.

As for bullets to use, I have recently bought some high-profile/tall 4mm bullets by ProTek. They seem to be the ONLY ones that have the taller design with the solder cup. To me, these provided a taller, "more-grippable" design, especially if they're tight in the tubes--which they are indeed--AND they provide a clean and easy method of soldering. They also are VERY tight, which kind of worries, me actually. There's tight and snug...and then there's too tight!

The Trinity/Revtechs posted above look to be a good design, but I needed 4mm, not 5mm, and at $7.50 for a pair, that's a bit steep, IMO. The design is probably the best I've seen, however, as long as 12AWG wire can be inserted cleanly into the window for soldering in the cup.