Nostalgia: XM177/CAR-15 Handguards. Simple, inexpensive , lightweight, good at what they do.

Practical/Night Fighting: SOLGW L89 Rail. Solid, durable, rigid enough for MFAL use if you have one, plan on getting one, or think you might find one laying on the ground someday. Integrated QD swivels at the rear of the rail, and 7 sided MLOK.