We've been in exactly this situation. In a town with a number of schools, but only 2 that we would get a place at due to tightly defined GPAs and demand. One has a really poor behavioural and academic performance (but is working hard to change under newish leadership) and the other is the next weakest in the area in terms of academic performance, but it is does have better behaviour and stronger leadership.
Our DD is in year 6 now and took entrance exams for 2 of the 3 schools she was eligible to go for in the county. These are our closest selective schools and are both 25+ miles away. She had about 18 months of Atom Prime to help her prepare for the required standards, as well as a pretty dull summer last year, with slightly more regular exam preparation work.
She is pretty bright, but applications these places has gone up by about 2 to 3x per place over the past couple of years. She was also in the secondary catchment area for both schools, so was effectively needing to be somewhere around the top 10 to 20% of applicants to have a chance at the remaining places once the main catchment area places were filled.
It was quite a bit of work for her and for us, as well as being a very stressful September and October until we got the results. Fortunately in our county we get told if they have done enough to be offered a place, are on the waiting list, or haven't hit the required standard. She passed both, so it gave her and us a choice out of the two.
I don't regret doing what we did and hopefully it gives her a much better school opportunity than one of the two local ones. I fully understand why some parents do whatever they can to get their child in to a better school. Had ours not had the potential to pass the exams, then I'm sure we might have planned ahead and looked at a house move instead. I felt a lot of pressure to do as much as I could to give her the best opportunity with her schooling and hopefully we've achieved that.