I grew up in an area that had a really large Jewish population. This “putting jelly on bagels” thing is completely foreign to me, but I can accept sweet bagels as a compromise. However, the best bagels, IMO, are with savory toppings like cream cheese, lox, and possibly on a garlic, onion or everything bagel (sans salt).
cream cheese
Margarine. I was going to say butter, but decided to be accurate. However, if I order it someplace, I say butter.
Aww yeah! Food of the gods.
Ditto. (Philadelphia brand salmon cream cheese to be exact).
So, by “jelly”, I’m assuming like in PB&J? As opposed to Jello. (Which I’d call “jam”… and wouldn’t put on a bagel unless it was a raisin bagel… which I wouldn’t be eating). 
Usually cream cheese, sometimes butter, and if there’s lox available sometimes it goes on top of the cream cheese.
Never jelly, though.
Jelly is like jam, without the chunky bits.
Cream cheese + smoked salmon + red onion + capers.
Sometimes cream cheese if I’ve bought some specifically for that purpose, but usually it’s vegemite, slapped on THICK. Mmmmmmmm…
Ideally veggie cream cheese, or plain cream cheese and smoked salmon. Jelly just sounds gross on a bage.*
*I’m talking about proper, chewy water bagels, not those round things you get at grocery stores.