Best Spells for Lore Bard to Take at 6th level

[Asmotherion]

I'm a big fan of Counterspell and Find Steed myself.

I second that. I'd suggest Eldritch Blast, but it's better to take it via Warlock Dipping 2 for Agonising.

Depending on your Dex, Shadow Blade might be cool for you, together with Booming Blade, allowing you to gish a bit. If your Dex is not a good score of your character, don't go that way though.