I'm fine with both, though I do prefer having Simlish things since that's what the game came with. In my game I just interpret Simlish as the universal language, but they learn English too which became more common to use for names (since my sims's names are in English) because it "looked cool."

To me, Simlish is the primary language spoken by all Sims, but it is by no means the only language. I figure Sims can learn to speak English, French, Chinese, Khmer, German, Tagalog, Spanish, etc. if they wanted to; "human" languages thus exist in my game. I'm a bit more tolerant on English text in the game, although I still generally prefer Simlish text, if only because in all of my neighbourhoods Simlish is the primary and official language. Therefore, if I hang up an exit sign, or some safety/warning sign, I'd expect it to be written in Simlish so everyone can understand. EAxis actually did a fairly good job in their Sims games and in SimCity 4, where icons are used instead of text (The stop sign in The Sims: Hot Date was an icon of a stop hand signal, and did not feature any text). Creators for The Sims generally use Simlish more often than creators for SimCity games; really don't like seeing English in my SimCity 4 games.