In my post above I mentioned a hose pliers I see is also referred to as "circle" pliers (never heard that before) and I failed to add some pictures. I've added some pictures of the various items I've used, including a bent long nose pliers, the hose pliers (and yes they are bent on the end), and a small end nippers I have used which I've found to be better than those above. I like the hose pliers for pressing the tabs in on connectors.
However I agree with John, these don't always work and the hose pliers would run the risk of not pulling the connector out straight (likely obvious when you refer to the pictures I added that have also provide a side view).
@gunrunnerjohn I wonder if this long reach end nippers would be better (especially after trimming or removing the large grips)? Sorry if I didn't add this link correctly, first time I've done this:
SPEEDWOX Long Reach End Nippers 5-1/2 Inches Mini End Cutting Pliers Fine End Cutters
I am going to buy one and see how it looks. I could always heat up the handles and bend the a little if they are too wide, or even cut them off and re-weld them at a different angle. If nothing else with the long reach it will be a useful tool for other purposes.
Channellock of course sells has its #748 8" long reach end nipper, which would have plenty of reach, but I don't think the end is wide enough and likely awkward given the length of it and a little overkill for trains.
Of course if anyone is using an end nippers to pull these connectors, be careful because if you slip off the end...you just might cut the wires (ok, maybe I'm the only one that runs this risk ).
I suppose one could dull the nippers a little with a file (equally on each side), but maybe you'd lose gripping ability. Filed or not, the ends could be coated with Plastidip (or sprayed with liquid duct tape).