I invest in northern NJ like Shawn (3 small multi family properties last 4 years, all house hacks in Bergen county) and do fine. @Jonathan Greene is in Morris county and post content northern NJ specific, follow his YouTube channel. His short videos are gold. We've posted about it before but there are pros and cons to NJ. Quick list, pros- low vacancy rates, high rents, moderate/high home appreciation, high rents increases, demand is always there as people move/commute from NYC; cons- very competitive, pro tenant laws, high property taxes, some towns have rent control, high barrier to entry with expensive multifamily prices. James Wise is right, NJ is tenant friendly however it is not as bad in more purple/red counties. Eviction court and judges are more moderate and reasonable. Essex and Hudson county are blue (high property taxes too) and I would never buy there. The surrounding counties aren't as bad, talking with local attorneys and investors. If you're interested in reading the basics, read this.
https://www.nj.gov/dca/divisions/codes/publications/pdf_lti/...
I'm not familiar with Morristown and Morris county specifically but made two offers on East Rutherford duplexes. Lost out on both but the proximity to NYC is very attractive and the town is decent. You need to pick at least a county in NJ IMO.. Also I'd say house hacking small multi is the best strategy to start building up (biased as that's what I did) but you have a primary so that's tough. If you don't have a ton of cash then NJ may be tough for you due to high price points (looking at 150k minimum for down payment and closing cost). Most people who are interested in NJ investing I meet never get started or invest out of state. The ones who do invest here seem to do very well. I always see people crap on REI in NJ without knowing specifics. On the surface it may look bad, but my portfolio is pretty solid for only house hacking. @Sunny Burns is even more impressive and was on the BP podcast way back when.