I think that in this particular instance, .*? ought to be fine, as embedded font tags are not legal (whereas in Ovid's example, embedded "s are fine).

In this case we're looking for stuff between <font ...> and </font> so .*? works a charm, although, if you had code that had:

<font ..> text <font ..> more text </font> and some </font>
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you'd get

text <font ..> more text
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out. This would be awkward, but a negated character class won't save us. If it is possible that you're getting insane html, then you have to expect bugginess on any regexp we come up with.