Never one to avoid a good bandwagon, here I go with my favourites of various things:
My current favourites are Ambush Alley's Force on Force/Tomorrow's War for skirmish gaming, and Volley and Bayonet for Horse & Musket. I thought Black Powder would own my heart forever, but alas! VnB is a better fit for how I like my horse & musket battles - big and at an army level, rather than brigade.
For years, I was a dedicated 20mm man (outside the obligatory flirtations with GW's stuff), but I've recently turned to 15mm for skirmish level games and 2mm for large-scale warfare. The scenery is easier to store (you can fit giant towns onto CDs and keep them in a doublesized CD case in 2mm), and the figures take up appreciably less room - particularly the vehicles.
I have to plump for Zvezda for long-term favourites, although Irregular's 2mm range is quickly catching up!
I don't really watch films for wargaming inspiration, but if I did, Lord of the Rings and Black Hawk Down would have to be my favourites. If TV counted, Band of Brothers would win hands down.
Now books, there's something different! I vote Doug Beattie's Task Force Helmand or C S Grant's classic Wargame Campaigns, they have inspired me massively ten years apart from each other.
There can only be one here. Not Wargames Illustrated, not White Dwarf (although I did like it under Paul Sawyer).
Miniature Wargames is the winner hands down - since I was ten it has been a source of amazement and pleasure!
I encourage others to try this list - although I was lazy and entered multiple contestants to most categories, thinking about the different categories made me really consider what is important to me in my wargaming.