I'm playing my first game of 5e and I rolled a paladin since I never have and they seem more enjoyable in this version.
After looking at the new stuff it seems like using a whip and a hand crossbow as a vengeance paladin could play out well. If you have Hunter's Mark up (vengeance lv1 extra spell) and take the Crossbow Expert feat, you can make a bonus action attack with the crossbow when you make a melee attack so you're getting a nice 2d6 from the mark plus the weapon damage from both at 10ft range with the potential to smite (ability) for more damage with the whip and if you have a smite (spell) ready you're looking at some nice damage potential at lower levels if you don't mind burning spells. Also, if you use your vow of enmity you're getting advantage on all of the attack rolls.
So a level 4 Paladin with Thunderous smite ready and hunter's mark up who chooses to use their divine smite is potentially doing 1d4 + str/dex mod + 1d6 + dex mod +2d6 (spell smite) + 2d8 (divine smite) + 2d6 (hunter's mark weapon damage) which is 8-50 + modifiers damage with 10 ft knockback and prone on a failed strength check, an additional 1d8 to undead and fiends, and if you use the vow you get advantage on the attack rolls.
The issue with the above being that as a level 4 paladin you just used up all of your spells for the day in one ridiculous attack. The nice thing about hunter's mark is it can be transferred as a bonus action after the target reaches 0 on any subsequent turn during the 1 hour effect so you can just bounce that around and still do both weapon damages and 2d6 on a target (not on the same turn but it's still nice)
Also at lvl 7 with the Vengance Paladin you can move half your speed after making an attack of opportunity that doesn't provoke one in return which you're going to do a lot more of with a whip.
Seems like a nifty concept and I'm trying it out but, again, not the most solid on this edition so what I've thought up may not even work although it seems like a decent whip build.