I'm writing this on a Dell XPS15, bought June 2014. I also bought and used a Macbook in Dec 2008/Jan 2009 until I got the XPS.
Reliability wise the XPS has had minor faults (keyboard replaced at end of 3 year warranty, batteries swell after 3 1/2 years). The Macbook had a known-unreliable component fail requiring a replacement mainboard. There were issues with USB port reliability, the Macbook ports becoming unreliable after just a couple of years. The Dell has had windows updates regularly without trouble, but the Macbook had significant trouble when upgrading from Leopard to Snow Leopard, resulting in data loss and a 2 week period when it was unable to print (a commonly noted problem at the time). Battery life was similar then, but the new macbooks based on M series chips have amazing battery life. Other issues: Windows and OSX managed workflow differently, so when I needed to have around 20 word and excel files open at the same time to collate information, working under OSX was difficult because it was hard to select the right document, while under windows it was very easy. Finally I found performance after 5 years on the Macbook to have become frustratingly poor, while the Dell is still acceptable for doing photo-editing when travelling at nearly 9 years old.
Only you will know which is right for you. If battery life is a major factor then the macbook is the obvious winner. However if you are familiar with Windows there is a strong chance you'll find OSX frustrating to use *in some areas*. I was quite tempted last year to pick up an M1 mini, but it's just more trouble than it's worth.