I'm not sure I can really answer that without offending someone. I will try in hopes that folks don't take offense. Side note the Oneway lathe was used by a renowned bowl turner who now is retired and has been for a long time. I think that those who chose the Vicmarc did so because it has proven to be a work horse with few problems and it is a no frills lathe at a decent price. In addition the turners chucks and accessories will work pretty well anywhere they go, unfortunately for oneway they won't change their thread size. I also looked at the oneway 2416 (turned on one - did not core on the 2416 - I did on a 1220 it worked but was under powered for coring especially if you core a lot) and had it down to it and the Vicmarc. It came down to how much I was going to have to spend to re-tool my shop. I also was put off by the swing arm on the Oneway even though I think that is one of those things you can get muscle memory with as you use it. I spoke with a few production bowl turners and they felt the same as you and I that a fixed head for turning a lot of larger bowls and coring was important. Sliding head stock lathes have a use for a lot of turners who turn some of this and some of that, meaning bowls, hollow forms and etc. If you are planning to turn mainly larger bowls as you mentioned Vicmarc, Oneway and Stubby will provide you with the confidence that nothing will ever be able to slip, plenty of power, plenty of mass and a history of performance. Unfortunately for Stubby they don't have much of a presence here and they can be a little more cumbersome to set up but once set for bowls they should be set (I also looked at this lathe but at the time you couldn't get them here). Having said that lathes excel in different areas. For example the Robust lathe excels in areas like hollow forms over the Vicmarc and Oneway, the 3520 also excels in areas over the Vicmarc and Oneway and Robust (cost for a hobbyist ----- pro who turns medium to small items ----- demonstrations). The Vicmarc and Oneway excel over the Robust and 3520 in bowls and heavy lifting. I wouldn't tell someone to buy a Vicmarc if they said I love turning pens or I only turn hollow forms, the Vicmarc works for that but there are better lathes for those applications. In short if your mainline is bowls you cannot go wrong with Vicmarc or Oneway. Like I said earlier do you like White or Blue?
Note only a few lathes mentioned above. There are a lot of good lathes out there for their applications. This thread is about bowl turning so I tried to stay in that lane. I am not a professional turner so take the above comments accordingly.