Out of 5 non-multiclass PCs that just made level 4 in our game, 3 of them took feats: Alert, Mobility, and Sentinel. The Fighter now has 2 feats. All of these feats were taken for melee and not for spell casting. The Wizard (myself) waffled between 18 Int and Magic Initiate (for Hex and Eldritch Blast), but I decided that this was a short term solution to a long term issue of me rolling bad and the Wizard being wimpy. With more spells at his disposal, this problem should start disappearing.
But, all of these feats (at least in our game) were taken in order to boost melee capabilities, not spell casting capabilities. The Cleric rarely casts a spell in combat and has a Str of 16 and took Alert in order to go early and often (and the player also was playing the PC cleric in LMoP who got ambushed a lot, so I'm thinking that influenced the decision as well). The Bard has low AC, so Mobility will be used to get in, melee attack, and then get out. And the Fighter took Sentinel since he has the Parry combat maneuver and Heavy Armor Master already and can absorb a lot of damage. He wants to be sticky and having foes fighting him instead of someone else. Now that the concept of 4E healing surges is gone, the more foes that attack him, the better since he can be healed ad infinitum (or at least until the party runs out of healing).
So yeah, from my experience so far, spells appear to be better with stat boosts than with feats. There is always an exception, but nothing shouts out, especially until the stat gets to 20.
Eventual Ritual Caster for Sorcerer?
Eventual Warcaster for Valor Bards or front line Clerics?
Sure, this makes sense as does several other combinations. Whether a given player sees the value before level 12 depends on many things including party makeup.