W!Chrom or W!Lissa

Chrom, without a doubt.

Definitely Chrom. If Lissa were +Atk or +Def, I'd suggest using her instead. But +Spd -Def is defintely a bad boon/bane for her

Chrom absolutely, you have one of the best natures for him.

Your Chrom is absolutely perfect, while your Lissa is far from perfect.

If you want him to be a purely offensive unit, then yes, that Bold Fighter would make him a beast. Give him Death Blow and he'll pretty much ORKO the entire roster of heroes except maybe Zelgius, Zephiel or other super high defense reds, which you wouldn't throw him against anyway.

That said, he truly shines with DC, so I'd pull for LA! Hector.
If you get a good one (+res/+atk/+def with -spd), then I'd sack Lissa to Hector, if you pull a bad Hector, feed both to Chrom and watch as he becomes the MVP of your team.

Mine is +atk/-res (I wish I kept my +res/-spd though) and he decimates things with DC/BF.