It's true there's a parallel-structure problem in the first sentence, but the second sentence is far from correct. Among other things, the verb "enjoy" idiomatically takes the gerund, not the infinitive.
1a) I enjoy watching baseball.
1b) I enjoy to watch baseball.
(awkward and wrong)
Furthermore, we already have the verb "like" --- that single verb is sufficient to cover both terms of the parallel structure --- we don't need a second verb. Here are a couple possible corrections:
2a) I like to run through forests more than to walk through crowds.
2b) I like running through forests more than walking through crowds.
2c) I enjoy running through forests more than walking through crowds.
All three of those are now correct. Notice, while the verb "enjoy" can only take the gerund, the verb "like" can take either the gerund or the infinitive.
These sentences, while correct, are not quite worth of the GMAT because they have an air of colloquialism. They are not formal enough. A more typical GMAT sentence would not be in the first-person and would use somewhat more elevated language. Unlike Walt Whitman, Henry David Thoreau had far more of a penchant for lingering in the stillness of the forest than for soaking up the energy of a bustling crowd.
Now, that's a GMAT SC type sentence --- historical figures, formal language, comparisons at different levels, and parallel structure.
Does all that make sense? Please let me know if you have any further questions.
Magoosh Test Prep