This is the single most common misunderstanding I deal with. A tenant signs a one-year lease, the year runs out, and they assume they're either being evicted or obliged to sign again. Neither is true.
What actually happens at the end of the term
Under Ontario's Residential Tenancies Act, when a fixed-term tenancy ends and neither party has given proper notice, the tenancy automatically continues as a month-to-month tenancy. Same unit, same rent, same terms. Nothing needs to be signed. Nothing lapses.
You are not required to sign a new fixed-term lease when the first one expires, and a landlord cannot evict you simply for declining to. Going month-to-month is a normal, lawful outcome, not a grey area.
Which is better for you?
Staying month-to-month
Maximum flexibility. You can leave on 60 days' notice at any point. Rent increases still require the standard 90 days' written notice on the proper form, and are still limited by the annual rent increase guideline where the unit is covered by it.
Signing another fixed term
Locks your rent for the length of the term, which matters if you expect increases. The trade-off is that you generally cannot leave early without the landlord's agreement or finding someone to assign or sublet to.
Rent increases
For most units, an increase requires 90 days' written notice on the province's form, can only happen once every twelve months, and is capped by the annual rent increase guideline Ontario publishes each year.
Units first occupied for residential purposes after 15 November 2018 are exempt from the guideline. The 90-day notice and once-a-year rules still apply, but there is no cap on the amount. A great many newer GTA condos fall into this category. If you're renting a recently built unit, ask when it was first occupied before you plan around a predictable increase.
The guideline changes every year. Confirm this year's number on Ontario's website rather than relying on what a friend paid last year.