I know this is an old thread, but I just have to contribute:
First off, let me say how much I admire this question being asked and the genuine good sportsmanship it displays, especially by asking after the enjoyment of BOTH players.
I have seen a lot of very intelligent and insightful posts regarding rules, composition, tactics, and unit efficiency that I am sure will be immensely helpful, but that have also caused me a slight measure of trepidation as a gamer who is far more casual than competitive.
I will probably not optimise my lists, preferring to field what feels"right" as an army. I also tend to shy away from named characters in smaller games (below 2.5k points) as it seems wrong to have galactically renowned individuals involved in every minor engagement.
So, enjoyment will always trump competitiveness for me, and that is why I found this thread so encouraging. However, a simple "How do I play for fun instead of playing to win?" thread could have done that. What I find truly admirable about this topic is that it seeks to make the game an enjoyable experience for one's opponent too, something I believe to be indispensable to the ethos of the hobby.
Yes, you are engaging in a strategic wargame, and a struggle for victory is certainly part of the fun, but one should remember that the person across the table from you is a fellow hobbyist and enthusiast, not an actual enemy to be defeated at all costs.
Striving for victory should serve to facilitate the players enjoyment by providing them with an engaging challenge. After all, this is a game, and enjoyment is the primary aim of games. once the struggle for victory becomes unenjoyable, it is no longer serving it's purpose.
Now obviously the level of challenge that someone finds enjoyable will be different for every player, and some will not be satisfied unless you force them to use every last ounce of brain power and strategy available (they're probably the sort of people who install new games and instantly select the "insanity" difficulty option) but in every case you should be able to walk away from the table and still be friends with your opponent, and with both of you still enjoying the hobby.
After all, this is 40K not monopoly